US5136989A - Two-stroke cycle internal combustion engine - Google Patents

Two-stroke cycle internal combustion engine Download PDF

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Publication number
US5136989A
US5136989A US07/698,464 US69846491A US5136989A US 5136989 A US5136989 A US 5136989A US 69846491 A US69846491 A US 69846491A US 5136989 A US5136989 A US 5136989A
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United States
Prior art keywords
exhaust
crankshaft
control member
internal combustion
edge
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Expired - Fee Related
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US07/698,464
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Albin Sterbenz
Franz Laimbock
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
    • F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
    • F02D13/028—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation for two-stroke engines
    • F02D13/0284—Variable control of exhaust valves only
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • This invention relates to a two-stroke cycle internal combustion engine designed for crankcase scavenging and comprising an exhaust passage which extends from an exhaust port in the cylinder wall and which contains a control member, which is adjustable in the direction of travel of the piston to adjust the flow area of the exhaust port in dependence on one or more operational parameters of the internal combustion engine, in particular, in dependence on its speed.
  • Two-stroke cycle internal combustion engines of that kind are already known, e.g., from British Patent Specification 2,177,755, U.S. Pat. Nos. 4,516,530, and 4,768,473.
  • the control member is so arranged and designed that it is operable to adjust that edge of the exhaust port which is remote from the crankshaft in order to prolong or shorten the exhaust time in dependence on speed in adaptation on the operating conditions.
  • British Patent Specification 2,177,755 it is also known to provide two lateral exhaust passages in addition to a main exhaust passage and also to provide an air chamber, which is closed to the outside and adapted to be connected to the exhaust system.
  • control member serves also for selectively closing the lateral exhaust passages and the air chamber so that the opening period of the main exhaust passage and of the lateral exhaust passages can be reduced during an operation at low speed whereas during an operation at high speed the flow areas of the exhaust passages can be entirely opened and the air chamber can be closed in order to increase the power of the engine.
  • the scavenging losses cannot be decreased by such measures.
  • control member conforms to the flow lines in the exhaust passage and constitutes that edge of the exhaust port which is nearer to the crankshaft and said control member is movable to adjust said edge.
  • the exhaust passage consists of a main exhaust passage and two lateral exhaust passages which adjoin respective exhaust ports
  • said lateral exhaust passages can be closed in accordance with the invention by the control member when it is in its end position remote from the crankshaft. This will also improve the exhaust behavior and the driveability of the internal combustion engine during an operation at low speeds and under light loads.
  • the effect of the control member may be improved if fresh gas contained in the exhaust system is recycled to the charge even during an operation at low speeds.
  • an air chamber may be provided, which is closed toward the outside and adapted to be connected to the exhaust system, and the control member may be coupled to the means for closing said air chamber in such a manner that the air chamber will be opened as the control member is moved toward its end position that is remove from the crankshaft.
  • the air chamber will be opened so that the torque can be increased and the pollutant content of the exhaust gas will be decreased further.
  • FIG. 1 is a longitudinal sectional view on a plane which extends through the cylinder axis of a two-stroke cycle internal combustion engine designed for crankcase scavenging; the control member is shown in its end position that is remote from the crankshaft.
  • FIG. 2 is a similar view showing those parts which are essential for the invention with the control member in its position for an operation at higher speeds or under heavier loads.
  • FIG. 3 is an associated transverse sectional view taken on line III--III in FIG. 1.
  • FIG. 4 is an external elevation showing on a larger scale those parts by which the control member is coupled to the means for closing the air chamber.
  • the two-stroke cycle internal combustion engine in accordance with the invention comprises a crankshaft 1, an associated piston 2 and a cylinder 3. Transfer passages 4 for the air-fuel mixture lead from the crankcase into the cylinder 3.
  • An exhaust passage 6 extends from an exhaust port 5 formed in the cylinder wall and contains a control member 7, which conforms to the flow lines in the exhaust passage 6 and is mounted to be adjustable by means of a shaft 8 so that that edge 9 of the exhaust port 5 which is nearer to the crankshaft can be adjusted in the axial direction of travel of the piston 2. As is particularly apparent from FIG.
  • the exhaust passage consists of a main passage 6 and of two lateral exhaust passages 6a, which adjoin respective exhaust ports 5a and are arranged to be closed by the control member 7 when it is in its end position remote from the crankshaft, as is shown in FIGS. 1 and 3.
  • the exhaust system of the internal combustion system comprises an air chamber 10, which is closed toward the outside and is adapted to be connected to the remainder of the exhaust system and by means of a rotary valve 11 can be closed or opened toward the exhaust passage 6.
  • the shaft 8 for the control member 7 is coupled to a gear 14 on the shaft of the rotary valve 11 by means of a rod 13, which terminates in a toothed segment 12.
  • the arrangement is such that the rotary valve 11 will be open when the control member 7 is in its end position remote from the crankshaft (FIG. 1) and will be closed when the control member 7 fully exposes the exhaust port 5 (FIG. 2).
  • a rotation is imparted to the rotary valve 11 by a servomotor via Bowden cables 15.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Characterised By The Charging Evacuation (AREA)
  • Cylinder Crankcases Of Internal Combustion Engines (AREA)
  • Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)

Abstract

A two-stroke-cycle internal combustion engine designed for crankcase scavenging has an exhaust passage, which extends from an exhaust window in the cylinder wall and which contains a control member, which is adjustable in the direction of travel of the piston to adjust the flow area of the exhaust window in dependence on one or more operational parameters of the internal combustion engine, in particular, in dependence on its speed. In order to minimize the scavenging losses and to permit the engine to combust even very lean mixtures while having a good drivability, the control member conforms to the flow lines in the exhaust passage and constitutes that edge of the exhaust window which is nearer to the crankshaft and said control member is movable to adjust said edge.

Description

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a two-stroke cycle internal combustion engine designed for crankcase scavenging and comprising an exhaust passage which extends from an exhaust port in the cylinder wall and which contains a control member, which is adjustable in the direction of travel of the piston to adjust the flow area of the exhaust port in dependence on one or more operational parameters of the internal combustion engine, in particular, in dependence on its speed.
2. Description of the Prior Art
Two-stroke cycle internal combustion engines of that kind are already known, e.g., from British Patent Specification 2,177,755, U.S. Pat. Nos. 4,516,530, and 4,768,473. But in those known engines the control member is so arranged and designed that it is operable to adjust that edge of the exhaust port which is remote from the crankshaft in order to prolong or shorten the exhaust time in dependence on speed in adaptation on the operating conditions. From British Patent Specification 2,177,755 it is also known to provide two lateral exhaust passages in addition to a main exhaust passage and also to provide an air chamber, which is closed to the outside and adapted to be connected to the exhaust system. In that case the control member serves also for selectively closing the lateral exhaust passages and the air chamber so that the opening period of the main exhaust passage and of the lateral exhaust passages can be reduced during an operation at low speed whereas during an operation at high speed the flow areas of the exhaust passages can be entirely opened and the air chamber can be closed in order to increase the power of the engine. But the scavenging losses cannot be decreased by such measures.
In internal combustion engines in which the pollutant content of the exhaust gas is minimized and in which exhaust systems comprising a catalytic converter can be used, it is essential to minimize the emission of pollutants from the internal combustion engine. For this reason the scavenging losses should be minimized and the internal combustion engine is desired to combust even very lean mixtures while having a good driveability.
SUMMARY OF THE INVENTION
For this reason it is an object of the invention so to improve the internal combustion engine described first hereinbefore that said requirements will be met.
The object set forth is accomplished in accordance with the invention in that the control member conforms to the flow lines in the exhaust passage and constitutes that edge of the exhaust port which is nearer to the crankshaft and said control member is movable to adjust said edge.
During an operation of the internal combustion engine at low speeds or under light loads, that edge of the exhaust port which is nearer to the crankshaft is displaced toward the combustion chamber, away from the crankshaft, so that the exhaust port is reduced in size. A favorable influence is thus exerted on the change of the cylinder charge so that the scavenging losses are decreased. This permits the use of a distinctly leaner air-fuel mixture which is supplied whereas the driveability of the internal combustion engine will not adversely be affected and cyclic fluctuations and misfires will not be induced. This will result in lower concentrations of unburnt hydrocarbons in the still existing scavenging losses so that the fuel consumption will be decreased. The displacement of that lower edge of the exhaust port which is nearer to the crankshaft in the direction from the crankshaft toward the combustion chamber will not change the control time but will change only that flow area of the exhaust passage which is associated with the instantaneous crank angle, i.e., the time-dependent flow area. Because the control member conforms to the flow lines, the adverse influence on the flow conditions in the region downstream of the exhaust port will be minimized.
In an internal combustion engine in which the exhaust passage consists of a main exhaust passage and two lateral exhaust passages which adjoin respective exhaust ports said lateral exhaust passages can be closed in accordance with the invention by the control member when it is in its end position remote from the crankshaft. This will also improve the exhaust behavior and the driveability of the internal combustion engine during an operation at low speeds and under light loads. The effect of the control member may be improved if fresh gas contained in the exhaust system is recycled to the charge even during an operation at low speeds. For this reason an air chamber may be provided, which is closed toward the outside and adapted to be connected to the exhaust system, and the control member may be coupled to the means for closing said air chamber in such a manner that the air chamber will be opened as the control member is moved toward its end position that is remove from the crankshaft. When in such an arrangement that edge of the exhaust post which is nearer to the crankcase is in its end position that is remove from the crankshaft, the air chamber will be opened so that the torque can be increased and the pollutant content of the exhaust gas will be decreased further.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a longitudinal sectional view on a plane which extends through the cylinder axis of a two-stroke cycle internal combustion engine designed for crankcase scavenging; the control member is shown in its end position that is remote from the crankshaft.
FIG. 2 is a similar view showing those parts which are essential for the invention with the control member in its position for an operation at higher speeds or under heavier loads.
FIG. 3 is an associated transverse sectional view taken on line III--III in FIG. 1.
FIG. 4 is an external elevation showing on a larger scale those parts by which the control member is coupled to the means for closing the air chamber.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
An illustrative embodiment of the invention will now be described more in detail with reference to the drawing.
The two-stroke cycle internal combustion engine in accordance with the invention comprises a crankshaft 1, an associated piston 2 and a cylinder 3. Transfer passages 4 for the air-fuel mixture lead from the crankcase into the cylinder 3. An exhaust passage 6 extends from an exhaust port 5 formed in the cylinder wall and contains a control member 7, which conforms to the flow lines in the exhaust passage 6 and is mounted to be adjustable by means of a shaft 8 so that that edge 9 of the exhaust port 5 which is nearer to the crankshaft can be adjusted in the axial direction of travel of the piston 2. As is particularly apparent from FIG. 3 the exhaust passage consists of a main passage 6 and of two lateral exhaust passages 6a, which adjoin respective exhaust ports 5a and are arranged to be closed by the control member 7 when it is in its end position remote from the crankshaft, as is shown in FIGS. 1 and 3.
The exhaust system of the internal combustion system comprises an air chamber 10, which is closed toward the outside and is adapted to be connected to the remainder of the exhaust system and by means of a rotary valve 11 can be closed or opened toward the exhaust passage 6. The shaft 8 for the control member 7 is coupled to a gear 14 on the shaft of the rotary valve 11 by means of a rod 13, which terminates in a toothed segment 12. As is apparent from FIGS. 1 and 2 the arrangement is such that the rotary valve 11 will be open when the control member 7 is in its end position remote from the crankshaft (FIG. 1) and will be closed when the control member 7 fully exposes the exhaust port 5 (FIG. 2). A rotation is imparted to the rotary valve 11 by a servomotor via Bowden cables 15.

Claims (1)

We claim:
1. In a two-stroke-cycle internal combustion engine designed for crankcase scavenging and comprising
a crankshaft,
a cylinder disposed on one side of said crankshaft and extending toward said crankshaft in an axial direction of said cylinder and having a cylinder wall formed with an exhaust port which extends in said axial direction and has an edge proximal to said crankshaft,
means defining an exhaust passage opening into said cylinder through said exhaust port, and
a piston operatively connected to said crankshaft and movable in said cylinder in said axial direction and adapted to open and close said exhaust port,
the improvement comprising
a control member arranged in said exhaust passage and having an edge movable in said axial direction to control the flow area of said exhaust port in dependence on at least one operational parameter of said engine,
said control member edge constituting the proximal edge of said exhaust port for adjustment of said edge in said axial direction.
US07/698,464 1990-05-15 1991-05-10 Two-stroke cycle internal combustion engine Expired - Fee Related US5136989A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT106990 1990-05-15
AT1069/90 1990-05-15

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US5136989A true US5136989A (en) 1992-08-11

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US07/698,464 Expired - Fee Related US5136989A (en) 1990-05-15 1991-05-10 Two-stroke cycle internal combustion engine

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EP (1) EP0457753B1 (en)
JP (1) JPH0788776B2 (en)
DE (1) DE59100878D1 (en)
ES (1) ES2050525T3 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5379731A (en) * 1991-07-02 1995-01-10 Orbital Engine Company (Australia) Pty. Limited Multicyclinder two stroke cycle engine
US5598813A (en) * 1993-06-14 1997-02-04 Yamaha Hatsudoki Kabushiki Kaisha Internal combustion engine with exhaust control device
US5873334A (en) * 1997-10-22 1999-02-23 Polaris Industries Inc. Exhaust valve system for two-cycle engines
US20130008403A1 (en) * 2011-06-07 2013-01-10 Mahle Koenig Kommanditgesellschaft Gmbh & Co. Kg Symmetric extended porting

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2721656B1 (en) * 1994-06-23 1996-08-09 Peugeot Two-cycle internal combustion engine.

Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE719509C (en) * 1938-08-20 1942-04-10 Brennabor Werke Ag Two-stroke internal combustion engine
US4399788A (en) * 1981-04-02 1983-08-23 Bombardier-Rotax Gesellschaft Mbh Internal combustion engine comprising means for controlling the axial extent of an exhaust port in a cylinder
US4516540A (en) * 1980-04-21 1985-05-14 Outboard Marine Corporation Two-cycle internal combustion engine including means for varying cylinder port timing
US4541371A (en) * 1983-09-19 1985-09-17 Suzuki Motor Co., Ltd. Two cycle engine
GB2177755A (en) * 1985-07-03 1987-01-28 Piaggio & C Spa Control of exhaust gas flow in two-stroke I.C. engines
US4751899A (en) * 1986-05-20 1988-06-21 Honda Giken Kogyo Kabushiki Kaisha Two-cycle engine
US4768473A (en) * 1985-07-22 1988-09-06 Honda Giken Kogyo Kabushiki Kaisha Exhaust timing control apparatus
US4776305A (en) * 1986-05-20 1988-10-11 Honda Giken Kogyo Kabushiki Kaisha Exhaust timing control device for two-cycle engines
SU1474301A1 (en) * 1987-08-26 1989-04-23 Владимирский политехнический институт Two-stroke engine
US4945868A (en) * 1989-06-21 1990-08-07 General Motors Corporation Two cycle exhaust recycling
US4969329A (en) * 1989-05-05 1990-11-13 General Motors Corporation Two cycle engine with exhaust emission control
US4969330A (en) * 1989-06-21 1990-11-13 General Motors Corporation Two cycle engine catalytic emission control
US4993373A (en) * 1989-06-21 1991-02-19 General Motors Corporation Sealing shroud port timing valve for two cycle engine
US5063887A (en) * 1989-08-14 1991-11-12 Yamaha Hatsudoki Kabushiki Kaisha Exhaust control valve system for parallel multi-cylinder two-cycle engine

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3666716D1 (en) * 1985-07-22 1989-12-07 Honda Motor Co Ltd Exhaust timing control apparatus
US4829946A (en) * 1987-09-15 1989-05-16 Performance Industries, Inc. Exhaust control valve for two-stroke cycle engines and process for using the same

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE719509C (en) * 1938-08-20 1942-04-10 Brennabor Werke Ag Two-stroke internal combustion engine
US4516540A (en) * 1980-04-21 1985-05-14 Outboard Marine Corporation Two-cycle internal combustion engine including means for varying cylinder port timing
US4399788A (en) * 1981-04-02 1983-08-23 Bombardier-Rotax Gesellschaft Mbh Internal combustion engine comprising means for controlling the axial extent of an exhaust port in a cylinder
US4541371A (en) * 1983-09-19 1985-09-17 Suzuki Motor Co., Ltd. Two cycle engine
GB2177755A (en) * 1985-07-03 1987-01-28 Piaggio & C Spa Control of exhaust gas flow in two-stroke I.C. engines
US4768473A (en) * 1985-07-22 1988-09-06 Honda Giken Kogyo Kabushiki Kaisha Exhaust timing control apparatus
US4751899A (en) * 1986-05-20 1988-06-21 Honda Giken Kogyo Kabushiki Kaisha Two-cycle engine
US4776305A (en) * 1986-05-20 1988-10-11 Honda Giken Kogyo Kabushiki Kaisha Exhaust timing control device for two-cycle engines
SU1474301A1 (en) * 1987-08-26 1989-04-23 Владимирский политехнический институт Two-stroke engine
US4969329A (en) * 1989-05-05 1990-11-13 General Motors Corporation Two cycle engine with exhaust emission control
US4945868A (en) * 1989-06-21 1990-08-07 General Motors Corporation Two cycle exhaust recycling
US4969330A (en) * 1989-06-21 1990-11-13 General Motors Corporation Two cycle engine catalytic emission control
US4993373A (en) * 1989-06-21 1991-02-19 General Motors Corporation Sealing shroud port timing valve for two cycle engine
US5063887A (en) * 1989-08-14 1991-11-12 Yamaha Hatsudoki Kabushiki Kaisha Exhaust control valve system for parallel multi-cylinder two-cycle engine

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5379731A (en) * 1991-07-02 1995-01-10 Orbital Engine Company (Australia) Pty. Limited Multicyclinder two stroke cycle engine
US5598813A (en) * 1993-06-14 1997-02-04 Yamaha Hatsudoki Kabushiki Kaisha Internal combustion engine with exhaust control device
US5873334A (en) * 1997-10-22 1999-02-23 Polaris Industries Inc. Exhaust valve system for two-cycle engines
US20130008403A1 (en) * 2011-06-07 2013-01-10 Mahle Koenig Kommanditgesellschaft Gmbh & Co. Kg Symmetric extended porting
US8662048B2 (en) * 2011-06-07 2014-03-04 Mahle Koenig Kommanditgesellschaft Gmbh & Co. Kg Symmetric extended porting

Also Published As

Publication number Publication date
JPH0788776B2 (en) 1995-09-27
DE59100878D1 (en) 1994-03-03
ES2050525T3 (en) 1994-05-16
JPH05195788A (en) 1993-08-03
EP0457753B1 (en) 1994-01-19
EP0457753A1 (en) 1991-11-21

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Effective date: 19960814

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